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1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 900
Preventive Maintenance and Root Cause Analysis of Sealed Quench
Furnace in Axle Heat Treatment Line
Dayananda Murthy T1, Dr. H. Yogish2, Dr. Rangaswamy3
PG Scholar, Department of Mechanical Engineering, SJCE, Mysuru -6
Associate Professor, Department of Mechanical Engineering, SJCE, Mysuru -6
Associate Professor, Department of Mathematics, BMSCE, Bangalore
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Abstract-The manufacturing industries are facing a
greater challenge in the market because of the various
factors like standardization, quality etc. One of the ways to
increase productivity is to increase the availability of the
existing machines. This can be achieved by reducing the
breakdowns of the machines. The Sealed quench furnace
performs various processes like carburizing, case
hardening and annealing are carried out for required
material properties of gear material in Axle heat
treatment line. When in final assembly the various
components are assembled into the axle housing to have
final product, many problems are faced. Problem like,
loading track getting damage, Quench oil circulation
pump coupling failure, Quench elevator air cylinder seal
failure, Delay in attaining required temperature, arise.
Therefore, to avoid this, Root-Cause Analysis of these
defects is carried out and the machine fixture unit is
modified as per the results of analysis.
In this present work, root cause analysis was adopted to
improve the machine availability & production capacity,
MTBF to certain extent and reduce the downtime and
MTTR of the machine and finally to prevent the failure of
equipment before it actually occurs. This present work
concludes that this will help the PLE department to
increase the machine availability & production capacity.
Keywords-Sealed Quench Furnace, RCA, Availability,
MTTR, MTBF.
1. INTRODUCTION
The critical machine was selected to conduct a present
work is Sealed quench furnace in the axle heat treatment
line of automotive axles limited. Sealed quench furnace is
a batch furnace where in the heating and quenching
chambers are combined in a single unit. The two
chambers are parted by a refractory-lined door which
can be opened to permit the hot charge to be conveyed
from the heating chamber to the cooling chamber
quench rack has two sets of rollers, one above the other
so, furnace can still be loaded at the same time as the
load just treated is still in the quench oil on the lower set
of rollers, the load just treated is being atmosphere
cooled on the upper rollers. Sealed quench furnaces
usually operate over the temperature range 750°C to
1000°C but can operate from 570°C to 1100°C with
appropriate modifications. hot zone consists of a steel
outer shell, which is lined inside with refractory bricks.
The load stands on a hearth which consists of a thick
ceramic plate with holes in it, supported by refractory
brick pillars which permit open circulation of the
controlled atmosphere. The charge is surrounded by the
controlled atmosphere which protects the components
from oxidation and provides the ideal environment for
carrying out treatments such as hardening, carburizing
and carbonitriding.
Fig-1: Schematic View of Sealed Quench Furnace
Fig- 2: Sealed Quench Furnace
Here there is a frequent and repetitive breakdown
related to both heating and quenching unit. Problem is
loading track getting damage, Quench oil circulation

2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 901
pump coupling failure, Quench elevator air cylinder seal
failure, Delay in attaining required temperature. Due to
this problem the machine availability is decreased and
this is a frequent breakdown. There was a decrease in
production capacity and MTBF. Hence in this present
work an attempt has been made to overcome the above
problems by incorporating new preventive maintenance
schedules with safety interlock. To obtain the new
preventive maintenance schedule. repeated breakdowns
were identified, inspected and analysed using Root cause
analysis technique like why- why analysis and fishbone
diagram. These techniques helped in increasing
availability and MTBF to certain extent and reduce the
downtime and finally to prevent the failure of equipment
before it actually occurs.
1.1 Methodology of Work
1. Study of production process
2. Setting the objectives for the study
3. Data collection for breakdown status
4. Analysis of the data collected
5. Selection of appropriate tools and techniques for
the study
6. Identify the breakdowns which are most critical
7. Finding the root causes of the breakdowns
a. Fishbone diagram
b. Why-why analysis
8. Implement of counter measures
9. Check the results
10. Improvement of a new preventive maintenance
schedule.
2. ROOT CAUSE ANALYSIS
RCA is a technique of evaluating a particular
problem/breakdown considering the important factors
which are responsible for that problem/breakdown to
arise. Root Cause is that, if corrected, would prevent
recurrence of the similar breakdown. The root cause
does not apply to this occurrence only, but has general
suggestions to a broad group of possible occurrences,
and it is the best fundamental aspect of the cause that
can logically be identified and modified. There may be a
series of causes that can be identified, one leading to
another. This series should be followed until the
essential, correctable cause has been identified. This
method is considered to be the most reliable method of
analysis in most of the industries. Many Root Cause
Analysis Tools have developed from the literature as
general standards for identifying root causes. Why-Why
Analysis tool was used to determine the root cause in
this present work.
2.1 Root Cause Analysis And Implementation
2.1.1 Break down description - Loading track getting
damage
Root cause - No proper rigid support for furnace track
Physical phenomenon - High temperature inside furnace
Table-1: Why-Why analysis of Loading Track
Problem Loading track getting damage
Why? Track getting bend due to high temperature
inside the furnace
Why? Temperature inside furnace is around 900˚C
Why? No proper rigid support for furnace track
Why? Original design was not proper
Counter measures - Extra strength provided by
introducing sillimanite Carbide bricks & SS 310 bracket
and cementing it from all side for rigid track.
Fig – 3: Before Counter Measure

3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 902
Fig – 4: After Counter Measure
2.1.2 Break down description - Delay in attaining
required temperature
Root cause - Original design was not proper
Physical phenomenon - Heat loss near burner area
Table -2: Why-Why analysis of Furnace Temperature
Problem Delay in attaining required temperature
Why? Required temperature was not maintained
throughout a cycle
Why? Heat loss near burner area
Why? Manual firing was not systematic
Why? Original design was not proper
Counter measures - Burner design modified close firing
provided with auto ignition
Fig -5: Before Counter Measure
Fig - 6: After Counter Measure
2.1.3 Break down description -Quench oil circulation
pump coupling failure
Root cause - Pump motor coupling Misalignment
Physical phenomenon - coupling spider failure
Table – 3: Why-Why analysis of pump
Problem Quench oil circulation pump coupling
failure
Why? Quench oil pump coupling spider failure
Why? Pump motor coupling Misalignment
Why? Fail in safe guard coupling
Why? Maintenance was not proper
Counter Measure - Coupling modified by using in house
flexible flat belt and flange.
Fig – 7: Before Counter Measure

4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 903
Fig 8: After Counter Measure
2.1.4 Break down description - Quench elevator air
cylinder seal failure
Root cause - Cylinder is only 100 mm away from the
furnace body
Physical phenomenon – High temperature
Table – 4: Why-Why analysis of cylinder seal
Problem Quench elevator air cylinder seal failure
Why? Piston seal leakage
Why? Temperature is high
Why? Cylinder is only 100 mm away from the
furnace body
Why? Original design was not proper
Counter measures - The cylinder height increased from
the furnace body to 1.4m.
Fig – 9: Before Counter Measure
Fig - 10: After Counter Measure
3. RESULTS
Table-5: Comparison of results before and after
implementation of counter measures of sealed quench
furnace
Fig - 11: Graph showing comparison of availability
before and after implementation of counter measures
Fig - 12: Graph showing comparison of MTBF before and
after implementation of counter measures

5. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072
© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 904
Fig -13: Graph showing comparison of MTTR before and
after implementation of counter measures
The usage of root cause analysis helped to identify the
correct causes of failures by which the suitable
countermeasures are developed and implemented. The
process measurable such as Availability, MTBF, and
MTTR are calculated before and after the
implementation of counter measures. Continuous
monitoring of processes is done after the
implementation of counter measures.
4. CONCLUSION
The following conclusions are drawn:
 The Availability of sealed quench furnace is
increased from 96.07 to 99.13%.
 The MTBF of sealed quench furnace is increased
from 78.66 to 230 hours.
 The MTTR of sealed quench furnace is
decreased from 3.21 to 2 hours.
 The Effectiveness of preventive maintenance of
sealed quench furnace is improved.
The Breakdowns such as loading track damage, Quench
oil circulation pump coupling failure, Quench elevator air
cylinder seal failure and delay in attaining required
temperature in sealed quench furnace is eliminated.
REFERENCES
[1] "Maintenance planning and control" - Anthony Kelly.
East west press Pvt. Ltd., 1984
[2] "Root cause analysis in aircraft final assembly" -
Brown J I. Master abstract international 1994
[3] “Management of Industrial maintenance” Anthony
kelly and M.I.Hrris Butterworth and co.Ltd.,1978
[4] Naveen K.J, Dr.H.Yogish, “Preventive Maintenance
and Root Cause Analysis of Soham Pre- Treatment
Washing Machine in Axle Assembly Line”
International Journal of Recent Trends in
Engineering & Research, Volume 02, Issue 07, July
2016.